vice president joe biden said to speak at the u.s. conference of mayors just about four hours from now, when that happens, cnn will bring it to you live. the president of that group, that mayor's group is philadelphia mayor michael nutter. he's a big obama supporter and during an appearance before a u.s. house committee nutter slammed the nra for this ad that criticizes the president for not wanting to put armed guards in schools while his own daughters get secret service protection. mayor nutter joins me now from washington. welcome, mr. mayor. >> good morning, carol, how are you? >> what did you object to in that nra ad? >> for those of us in the political business, generally it's been pretty much an unwritten but understood rule that family and children are out of bounds, that you don't attack someone's family, if you want to attack the candidate or the elected official, certainly that's your prerogative but generally family has been considered off limits, and that doesn't add anything to legitimate dialogue that really needs to ta